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Yz125 spark plug colour help!

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Sorry the pictures aren't the best but let me know what your think, 32:1 91 octane with 927 castor ( I usally run yamalube 2r)

Not sure if the jetting but I think it's stock

600 m above sea level

I ride somewhat hard but not full throttle all the time I go in the trails and the track.

Thanks for the help

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Sorry the pictures aren't the best but let me know what your think, 32:1 91 octane with 927 castor ( I usally run yamalube 2r)
Not sure if the jetting but I think it's stock
600 m above sea level
I ride somewhat hard but not full throttle all the time I go in the trails and the track.
Thanks for the help


300 to 600 m above sea level**

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That plug is far too clean and light colored, it should be inky black and dripping in oil.

Can't tell if your &%$#@!ing with me because my plugs used to last 30 mins and would be covered in oil....
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Plug reading tips: http://www.braigasen.com/howtoread.htm

you have to read deeper along the electrode, not just the tip and rim.

 

Pilot and needle circuits are adjusted by 'feel' and how the engine runs (throttle response, acceleration)

only main jet at wide open throttle is done by coloration and ideally also reading the piston carbon wash pattern.

 

Although your results don't seem oil fouled, you are using very high flash point premix oils for trail riding.

in recreational applications, "racing" oils aren't necessarily better.

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Plug reading tips: http://www.braigasen.com/howtoread.htm
you have to read deeper along the electrode, not just the tip and rim.
 
Pilot and needle circuits are adjusted by 'feel' and how the engine runs (throttle response, acceleration)
only main jet at wide open throttle is done by coloration and ideally also reading the piston carbon wash pattern.
 
Although your results don't seem oil fouled, you are using very high flash point premix oils for trail riding.
in recreational applications, "racing" oils aren't necessarily better.

From what you see is it good or to lean?

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Depends on the application and, how the engine was running/shut off before removing the plug.

My YZ125 is ridden on short straightaway MX tracks and sees very limited time at WOT, 

so in general  that tint looks 'just right' for me. (but your plug does seems to have a glossy wet look to it)

 

On an off-road ridden bike that sees sustained high rpms on long flat trail sections or forestry roads or

high loads like hill climbing & sand dunes, that's a tad too lean.

Edited by mlatour
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i wouldn't mind it a littler darker...personally. definitely richen the main before doing sustained WOT (sand, hill climbs).

it wouldn't hurt to peek inside the carb to see what jets/needle you are running. write it down in your service manual for future reference.

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i wouldn't mind it a littler darker...personally. definitely richen the main before doing sustained WOT (sand, hill climbs).
it wouldn't hurt to peek inside the carb to see what jets/needle you are running. write it down in your service manual for future reference.

Any links to jetting a yz125 for noobs?

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Start with the stock settings and fine tune from there according to YOUR conditions.

Jetting charts are a good baseline but it doesn't mean it will work out the same for you.

 

Charts are also meant for all out wide-open throttle MX racing, what the YZ125 was designed for,

Yamaha suggested settings will be too rich for general trail/off-roading and, too lean for sustained high rpm WOT stretches.

 

Again, taking into consideration you ride trail/off-road, from the stock setting one you can easily go 2 steps leaner on the pilot jet,

one clip position leaner on the needle and, two steps richer on the main jet.  Lean at low rpms so it runs crisp and doesn't foul, rich at high rpms to cool the engine.

 

Before you attempt to fine tune the jetting, you must be sure that absolutely everything else is correct with the engine.

Fresh silencer packing & reeds, float/fuel level properly set, no air/oil leaks (crank seals), fresh gas, clean air filter etc. etc.

Edited by mlatour
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I would not touch anything, best, cleanest plug I ever seen! Probably at perfect! Mine are good which is fine for me, that matches your riding spot on!

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I would not touch anything, best, cleanest plug I ever seen! Probably at perfect! Mine are good which is fine for me, that matches your riding spot on!

Well yeah for now one thing is I've been riding for 4 months so my riding progresses every ride, in a couple weeks I'm gonna be going to a track and practice hopefully be on the pipe more so I was thinking to richen it up

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 If at some point you believe you've been hammering, pull it again after 20 min and check, im sure you'll be fine 

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 If at some point you believe you've been hammering, pull it again after 20 min and check, im sure you'll be fine 

What does a plug that's too lean look like?

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